AIB (Agglomerative Information Bottleneck (AIB)) More...
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Classes | |
| struct | _VlAIB |
Typedefs | |
| typedef struct _VlAIB | VlAIB |
Functions | |
| VL_INLINE int | vl_aib_get_verbosity (VlAIB const *self) |
| Get the verbosity. | |
| VL_INLINE void | vl_aib_set_verbosity (VlAIB *self, int verbosity) |
| Set the verbosity. | |
Create and destroy | |
| VL_EXPORT VlAIB * | vl_aib_new (double *Pcx, vl_uint nvalues, vl_uint nlabels) |
| Allocates and initializes the internal data structure. | |
| VL_EXPORT void | vl_aib_delete (VlAIB *aib) |
| Deletes AIB data structure. | |
Process data | |
| VL_EXPORT void | vl_aib_process (VlAIB *aib) |
| Runs AIB on Pcx. | |
Retrieve results | |
| VL_INLINE vl_uint * | vl_aib_get_parents (VlAIB const *aib) |
| Get resulting list of parents. | |
| VL_INLINE double * | vl_aib_get_costs (VlAIB const *aib) |
| Get a list of merge costs. | |
Detailed Description
AIB (Agglomerative Information Bottleneck (AIB))
Definition in file aib.h.
Typedef Documentation
Function Documentation
| VL_EXPORT void vl_aib_delete | ( | VlAIB * | aib | ) |
| VL_INLINE double * vl_aib_get_costs | ( | VlAIB const * | aib | ) |
| VL_INLINE vl_uint * vl_aib_get_parents | ( | VlAIB const * | aib | ) |
| VL_INLINE int vl_aib_get_verbosity | ( | VlAIB const * | self | ) |
| VL_EXPORT VlAIB* vl_aib_new | ( | double * | Pcx, |
| vl_uint | nvalues, | ||
| vl_uint | nlabels | ||
| ) |
Allocates and initializes the internal data structure.
------------------------------------------------------------------
- Parameters:
-
Pcx A pointer to a 2D array of probabilities nvalues The number of rows in the array nlabels The number of columns in the array
Creates a new VlAIB struct containing pointers to all the data that will be used during the AIB process.
Allocates memory for the following:
- Px (nvalues*sizeof(double))
- Pc (nlabels*sizeof(double))
- nodelist (nvalues*sizeof(vl_uint))
- which (nvalues*sizeof(vl_uint))
- beta (nvalues*sizeof(double))
- bidx (nvalues*sizeof(vl_uint))
- parents ((2*nvalues-1)*sizeof(vl_uint))
- costs (nvalues*sizeof(double))
Since it simply copies to pointer to Pcx, the total additional memory requirement is:
(3*nvalues+nlabels)*sizeof(double) + 4*nvalues*sizeof(vl_uint)
- Returns:
- An allocated and initialized VlAIB pointer
| VL_EXPORT void vl_aib_process | ( | VlAIB * | aib | ) |
Runs AIB on Pcx.
------------------------------------------------------------------
- Parameters:
-
aib AIB object to process
The function runs Agglomerative Information Bottleneck (AIB) on the joint probability table aib->Pcx which has labels along the columns and feature values along the rows. AIB iteratively merges the two values of the feature x that causes the smallest decrease in mutual information between the random variables x and c.
Merge operations are arranged in a binary tree. The nodes of the tree correspond to the original feature values and any other value obtained as a result of a merge operation. The nodes are indexed in breadth-first order, starting from the leaves. The first index is zero. In this way, the leaves correspond directly to the original feature values. In total there are 2*nvalues-1 nodes.
The results may be accessed through vl_aib_get_parents which returns an array with one element per tree node. Each element is the index the parent node. The root parent is equal to zero. The array has 2*nvalues-1 elements.
Feature values with null probability are ignored by the algorithm and their nodes have parents indexing a non-existent tree node (a value bigger than 2*nvalues-1).
Then the function will also compute the information level after each merge. vl_get_costs will return a vector with the information level after each merge. cost has nvalues entries: The first is the value of the cost functional before any merge, and the others are the cost after the nvalues-1 merges.
| VL_INLINE void vl_aib_set_verbosity | ( | VlAIB * | self, |
| int | verbosity | ||
| ) |